JP2008192245A - Magnetic disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic disk device having a structure to suppress the deformation of the magnetic disk relating to the magnetic disk device, more specifically, in mounting of the magnetic disk to a hub. <P>SOLUTION: The magnetic disk device comprises alternately laminating the magnetic disks and spacers from a flange section at the bottom end of the hub secured to a spindle, securing a clamp which comes into contact with the magnetic disk in the uppermost part and presses the magnetic disks in an axial direction to the top end of the hub and holding the magnetic disks and the spacers between the clamp and the flange section. Recessed parts of a prescribed shape are formed on the surfaces of the spacers in contact with the magnetic disks. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic disk apparatus, and more particularly to a magnetic disk apparatus having a structure that suppresses deformation of a magnetic disk when the magnetic disk is attached to a hub.

Magnetic disk devices are indispensable as auxiliary storage devices for computers. In this magnetic disk apparatus, a plurality of magnetic disks, which are information storage media, are stacked on a hub via a spacer, and information is recorded and reproduced (read) by a magnetic head that floats on the surface of the magnetic disk while rotating the hub. Is supposed to do.
For example, FIG. 5 shows an example, and the magnetic disk 40 as a storage medium is a donut-shaped disk. The magnetic disk 40 is attached to the hub 30 with an annular spacer 50 interposed therebetween, and a clamp 60 is put on from above. The clamp 60 and the hub 30 are screwed together. The clamp 60 is screwed to fix the magnetic disk 40 and the spacer 50 between the clamp 60 and the flange portion of the hub 30. In FIG. 5, the number of magnetic disks 40 is two. However, there are many magnetic disk devices having more than that number, and in this case, the magnetic disks 40 and the spacers 50 are alternately stacked. The hub 30 is attached to a motor spindle (not shown) and is rotatable. The magnetic head 70 is floated by the air flow on the surface due to the rotation of the magnetic disk 40, and the magnetic field from the magnetic head acts on the recording medium on the surface of the magnetic disk through the gap to record information. Alternatively, information is read by sensing the magnetic field of the magnetic medium.
As described above, the magnetic head 70 reads and writes information while flying over the surface of the magnetic disk 40. However, since the flying height is very small, reading and writing are poor when the surface of the magnetic disk 40 is not smooth or wavy. In addition, data erasure and head crashes may occur due to contact of the magnetic head with the medium. Recently, the capacity of magnetic disk devices has been increased, and a flying height of 10 nm has been demanded. In particular, it has been required to reduce the undulation of the magnetic disk 40. As shown in FIG. 5, the magnetic disk 40 is held by the spacer 50, the flange portion of the hub 30, and the surface of the clamp 60. It is important to increase the flatness of the surfaces in contact with the magnetic disk 40. The surface is generally polished.
In order to solve the above problems, proposals have been made to define the surface roughness of the surface of the spacer or hub in contact with the magnetic disk so as to give minute irregularities, or to provide a plurality of grooves in the vertical direction on the outer peripheral surface of the spacer. . Accordingly, the stress distribution on the surface where the magnetic disk and the spacer are in contact is made uniform, or the stress is dispersed by the clamp load (Patent Document 1).
In addition, it has been proposed to form a plurality of convex portions having the same height on both edge surfaces in the axial direction of the spacer and hold the magnetic disk by the convex portions. It is supposed that deformation by pressurization by a clamp can be minimized because it is held by a convex portion (Patent Document 2).
JP 2004-348860 A Japanese Patent Application Laid-Open No. 08-50783

  As described above, the flying height of the magnetic disk device will become smaller in the future, and it is required to reduce the waviness of the magnetic disk in order to prevent head crash. Conventionally, in addition to processing the surface of parts such as spacers and clamps that come into contact with the magnetic disk smoothly, the handling in the cleaning process, strengthening the appearance inspection, cleaning the assembly environment, and optimizing the clamping force have been meticulous. Have been paying attention.

  However, there are no micro-protrusions due to burrs, scratches, dents, foreign matter, etc. on the surface that contacts the magnetic disk, such as spacers and clamps. In some cases, it causes deformation that causes undulation. For example, as shown in FIG. 6, when there is a minute protrusion 51 (for example, mixed foreign matter) on the surface where the spacer 50 is in contact with the magnetic disk 40 (hereinafter, also simply referred to as a contact surface), the magnetic disk 40 undulates at this portion. Will result. That is, the magnetic disk 40 is subjected to local stress due to the pressing by the clamp (the arrow shown in the drawing indicates the direction of pressing) and the microprojection hits, and this stress causes undulation.

  The methods proposed in Patent Document 1 and Patent Document 2 are methods for preventing the waviness of the magnetic disk, both of which are for the pressing force to be clamped, and the magnetic force generated by minute protrusions caused by burrs, dents, foreign matter, and the like. It does not suppress local stress on the disk.

  An object of the present invention is to provide a magnetic disk device that suppresses the generation of local stress on the magnetic disk even when the above-described minute protrusions are present, and minimizes the undulation.

The magnetic disk apparatus of the present invention is configured as follows.
(1) First invention
According to a first aspect of the present invention, a magnetic disk and a spacer are sequentially stacked from a flange portion at a lower end of a hub fixed to a spindle, and a clamp that contacts an uppermost magnetic disk and presses in an axial direction is provided on the upper end of the hub. A structure in which the magnetic disk and the spacer are sandwiched between the clamp and the flange, and a concave portion having a predetermined shape is formed on the surface of the spacer that contacts the magnetic disk (hereinafter also simply referred to as a contact surface). It is characterized by having formed.

By forming a recess on the contact surface of the spacer, the microprotrusion enters the recess, or when the microprotrusion is at the peak between the recesses, the peak is crushed by the pressing force of the clamp, Even if the stress is not applied or not, the stress is small, and as a result, the swell can be suppressed.
(2) Second invention The second invention is characterized in that, in addition to the spacer of the first invention, a concave portion having a predetermined shape is formed on the surface of the hub flange portion and the clamp contacting the magnetic disk. Is.

Even if the minute protrusion is on the contact surface between the flange portion and the magnetic disk of the clamp, the undulation can be suppressed for the same reason as in the first invention.
(3) Third invention The third invention is characterized in that, in the formation of the recesses in the first and second inventions, the shape of the recess is a recess formed in a groove or mesh shape. By adopting a groove or mesh shape, the size of the recesses and the ridge width between the recesses can be easily and accurately formed.
(4) 4th invention 4th invention WHEREIN: In formation of the recessed part in 1st-3rd invention, the area of a recessed part is a ratio of about 50% or more compared with the area of the flat surface before formation of the recessed part. It is characterized by being.

Whether or not the area of the concave portion is 50% or more means that the portion that is not a concave portion (which corresponds to the peak of the edge of the concave portion is referred to as a peak portion here) is less than 50. Therefore, by appropriately determining the size of the recess (for example, by using the statistical value of the size of the microprojection that has been generated in the past, the size of the recess is made several times larger), the microprojection becomes the peak portion. The probability of hitting can be reduced.
(5) Fifth Invention A fifth invention is a magnetic disk device having the same structure as that of the first invention, wherein a predetermined shape is provided between the magnetic disk and a spacer, a flange portion and a clamp in contact with the magnetic disk. A cushion sheet having a plurality of openings is inserted. The spacer, the flange portion, and the clamp have a flat contact surface with the magnetic disk as in the prior art, and use a cushion sheet having an opening as a substitute for the concave portion of the second invention.

  As described above, according to the present invention, the following effects can be obtained.

  According to the first invention, since the concave portion is provided on the contact surface of the spacer, even if there is a fine projection, the fine projection enters the concave portion, or when the fine projection is at the peak portion of the concave portion, the peak portion is pressed by the clamp. Therefore, it is possible to provide a magnetic disk device that suppresses swells.

  According to the second invention, in addition to the first invention, the concave portion is provided in the contact surface between the flange portion of the hub and the clamp, so that it is possible to provide a magnetic disk device in which the undulation is further suppressed.

  According to the third aspect of the invention, since the shape of the concave portion is a groove or mesh shape, the concave portion can be easily formed accurately.

  According to the fourth aspect of the present invention, the area of the concave portion is set to about 50% or more as compared with the flat surface. Therefore, the probability that the minute projections hit the contact surface of the spacer or the clamp decreases, and the undulation of the magnetic disk can be suppressed.

  According to the fifth invention, a cushion sheet having an opening instead of the recess is sandwiched between the contact surfaces, so that a magnetic disk device having the same effect as that of the second invention can be provided.

An embodiment of a portable information terminal will be described with reference to FIGS.
(Embodiment 1)
The first embodiment is an example in which a recess is formed in a flange portion of a spacer, clamp, or hub having a contact surface with the magnetic disk 40. FIG. 1 shows an example in which a V groove is formed as a recess on the contact surface of the spacer 100 with the magnetic disk 40. The groove width (interval between peaks) and depth shown in FIG. 1 are both 200 μm, and the peak width is 20 μm.

  In this case, the ratio of the area of the groove on the contact surface of the spacer 100 to the area before the groove is formed (a flat area without the groove) is about 90% (conversely, the peak that is a part in contact with the magnetic disk). The area ratio is about 10%). Therefore, since the size of the microprotrusions is about 30 μm at the maximum (when there is a microprotrusion larger than that, the spacer itself is removed by visual inspection), the microprotrusion fits in the groove and has no influence on the magnetic disk 40. There is a probability of not giving. Further, even if the minute protrusion hits the peak, the peak part is crushed by pressing with a clamp (the ridge part is formed thinly and becomes easy to be crushed because of the V groove), and the stress applied to the magnetic disk in that case is small Become. As a result, the occurrence of waviness of the magnetic disk 40 can be suppressed even if there are minute protrusions. In general, the width of the groove is preferably several times as large as 30 μm of the minute protrusion. Further, the area of the groove is desirably 50% or more with respect to the area without the groove.

  The material of the spacer 100 in FIG. 1 is SUS or aluminum. Since the contact surface of the spacer 100 has two upper and lower surfaces in FIG. 1, grooves are formed on both surfaces. Grooves are formed by etching or mechanical cutting, and deburring is performed by lightly polishing the entire contact surface as necessary.

  In FIG. 1, a V-groove is taken as an example of the shape of the recess, but it may be a square groove (or U-groove) as shown in FIG. 2 (a) or a mesh shape as shown in FIG. 2 (b). In the shapes shown in FIGS. 2A and 2B, the area ratio of the peaks shown in FIG. 1 is increased and the probability of hitting the minute protrusions is increased, but the pressing force is increased because the pressing by the clamp is dispersed. be able to.

  FIG. 3 shows an example in which a groove is formed on the contact surface between the clamp 200 and the flange portion of the hub. FIG. 3A shows a state in which the clamp 60 shown in FIG. 5B is inverted so that the contact surface of the clamp 200 can be seen, and grooves are formed on the contact surface. FIG. 3B shows an example in which a groove is formed in the flange portion of the hub 300 in the same manner as the clamp 200.

By forming grooves in the flange portion of the spacer 100 in FIG. 1, the clamp 200 in FIG. 3, and the hub 300, all the surfaces in contact with the magnetic disk 40 are provided with countermeasures against minute protrusions.
(Embodiment 2)
Embodiment 2 is an example of an embodiment of the cushion sheet 400. FIG. 4 (a) shows the shape, in which holes that are opened in a mesh shape are formed. Since the size of the hole to be opened is 30 μm with a large size of the minute protrusion, it is desirable that the size of the hole is several times as large. Moreover, it is desirable that the area of the hole to be opened is 50% or more with respect to the area without the opening. The material is aluminum or copper having a low Young's modulus, and the sheet thickness is 100 μm.

  FIG. 4B shows an example in which a cushion sheet 400 is sandwiched between contact surfaces of the magnetic disk 40 disposed between the clamp 60 and the spacer 50. The contact surface between the clamp 60 and the spacer 50 shown in FIG. 4B is the same as the conventional one and is flat. The cushion sheet 400 is tightened by the pressing force of the clamp 60 (arrow in FIG. 4B), and the local stress on the magnetic disk 40 exerted by the minute protrusions can be suppressed by the above-described mechanism.

  Although FIG. 4 shows an example of a mesh shape, holes may be formed like punching metal.

In addition to the above embodiment, the following additional notes are disclosed.
(Appendix 1)
Magnetic disks and spacers are alternately stacked from the flange portion at the lower end of the hub fixed to the spindle, and a clamp that contacts the uppermost magnetic disk and presses in the axial direction is fixed to the upper end portion of the hub. And a magnetic disk device for sandwiching the magnetic disk and the spacer between the flange portion and the flange portion,
A magnetic disk device, wherein the spacer is formed with a recess having a predetermined shape on a surface that contacts the magnetic disk.
(Appendix 2)
The magnetic disk device according to appendix 1, wherein a recess having a predetermined shape is formed on a surface of the hub where the flange portion and the clamp contact the magnetic disk.
(Appendix 3)
The magnetic disk device according to appendix 1 or appendix 2, wherein the concave portion is a recess formed in a groove or mesh shape.
(Appendix 4)
The magnetic disk device according to any one of supplementary notes 1 to 3, wherein the area of the concave portion is approximately 50% or more of the area of the flat surface before the concave portion is formed.
(Appendix 5)
Magnetic disks and spacers are alternately stacked from the flange portion at the lower end of the hub fixed to the spindle, and a clamp that contacts the uppermost magnetic disk and presses in the axial direction is fixed to the upper end portion of the hub. And a magnetic disk device for sandwiching the magnetic disk and the spacer between the flange portion and the flange portion,
A magnetic disk device, wherein a cushion sheet having an opening of a predetermined shape is inserted between the spacer in contact with the magnetic disk, the flange portion of the hub, and the clamp.
(Appendix 6)
The magnetic disk device according to appendix 5, wherein the material of the cushion sheet is aluminum or copper.
(Appendix 7)
7. The magnetic disk device according to appendix 5 or appendix 6, wherein the area of the opening of the cushion sheet is approximately 50% or more as compared to the area without the opening.

2 is an embodiment of a spacer according to the present invention. It is another example of a shape of a spacer. 1 is an embodiment of a clamp and hub according to the present invention. 2 is an example of a friction sheet according to the present invention. 2 is a configuration example of a magnetic disk device. It is a modification of the magnetic disk by the protrusion of the spacer surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Magnetic disk apparatus 20 Base 30 Hub 40 Magnetic disk 50 Spacer 51 Minute protrusion 60 Clamp 61 Clamping screw 70 Magnetic head 100 Spacer 200 Clamp 300 Hub

Claims (5)

Magnetic disks and spacers are alternately stacked from the flange portion at the lower end of the hub fixed to the spindle, and a clamp that contacts the uppermost magnetic disk and presses in the axial direction is fixed to the upper end portion of the hub. And a magnetic disk device for sandwiching the magnetic disk and the spacer between the flange portion and the flange portion,
A magnetic disk device, wherein the spacer is formed with a recess having a predetermined shape on a surface that contacts the magnetic disk. 2. The magnetic disk device according to claim 1, wherein a concave portion having a predetermined shape is formed on a surface where the flange portion of the hub and the clamp come into contact with the magnetic disk. The magnetic disk device according to claim 1, wherein the shape of the recess is a groove or a recess formed in a mesh shape. 4. The magnetic disk device according to claim 1, wherein the area of the recess is approximately 50% or more of the area of the flat surface before the recess is formed. 5. Magnetic disks and spacers are alternately stacked from the flange portion at the lower end of the hub fixed to the spindle, and a clamp that contacts the uppermost magnetic disk and presses in the axial direction is fixed to the upper end portion of the hub. And a magnetic disk device for sandwiching the magnetic disk and the spacer between the flange portion and the flange portion,
A magnetic disk device, wherein a cushion sheet having an opening of a predetermined shape is inserted between the spacer in contact with the magnetic disk, the flange portion of the hub, and the clamp.

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